Ultralong Cycle Life Of Lithium Oxygen Batteries Based On Biochar Materials

With the development of society and the advancement of science and technology,environment and energy have become two major themes.So,it's urgent to develop a chemical system of high specific energy,clean,safe.Lithium air/oxygen batteries show a high energy density,environmentally friendly,reversible and other advantages good application prospects.The dendrites growth and pierce the separator,exposed to the positive electrode,forming an internal short circuit,causing fever and even explosion,threatening batteries'safety.In addition,dendrite is easy to break in its grow thing process,reducing the amount of active materials and reduce the batteries'cycle life.The mechanism of lithium air batteries are base on the reaction of oxygen with lithium in non-aqueous electrolyte,and meanwhile,lithium oxides are deposited on air cathode.In general,the research on lithium air batteries is still in its initial stage and there are many obstacles must be solved in order to achieve long operating life and large discharge capacity.Therefore,we choose a kind of environment-friendly green materials,Miscanthus×giganteus,to prepare the positive oxygen electrode.In this study,we fabricated an activated carbon material with porous honeycomb-like structure by a KOH activation method from the earth-abundant MG.The MGACs have high surface area?1474 m²/g?and large pore volume?0.859 cm³/g?,which could be used as an oxygen electrode material in Li-O₂ batteries.The Li-O₂batteries with MGACs-based oxygen electrode exhibit high specific capacity?9400mAh/g at 0.02 mA/cm²?,long-life performance?601 cycles with a cut-off capacity of500 mAh/g at 0.2 mA/cm²?and good rate capability.All of facts proved that MGACs materials manifest a remarkably electrochemical activity towards the ORR/OER,especially to ORR.It certificates that MGACs materials will be a promising active material of oxygen positive electrode for development of excellent performance of Li-O₂ batteries.Moreover,due to the unlimited natural raw resources and convenient preparation technique,the instinct properties of environment friendly and resources independent of biochar-based battery will become a non-ignorable dominant in the long-term future development of secondary Li-O₂ batteries.In this paper,we study the performance of MGACs and MGNACs in lithium air/oxygen battery,and highlight the MGACs materials.Based on the catalytic activity and positive electrode structure.Additionally,the material exhibits high rate capability and high reversibility,which is an excellent candidates for the application in Li-O₂ batteries.